One-piece structural body for reflective pavement marker

ABSTRACT

A reflective pavement marker can be fabricated utilizing a typically used housing (shell) reinforced by agglutination of a one-piece, monolithically formed, hollowed structural body. The hollowed structural body is having a sealed, textured base surface and an upper, two sides and two face surfaces defined by load carrying partition walls forming multiple hollow cavities. This type of hollowed structural body can effectively replace various structural fill systems or any other multi elements structural body used in fabricating a reflective pavement marker. The hollowed structural body is generally welded or agglutinated directly to the interior of a housing (shell), and to portion of the apexes of the cube corner reflective elements within said reflective faces of a housing. This type of hollow structural body can be formed to fit any single piece housing fabricated with integrally molded retro-reflective faces.

FIELD OF INVENTION

[0001] This invention relates to roadway markers that are used fortraffic lane delineation, in particular, to markers with simplified, lowcost structural body.

BACKGROUND OF THE INVENTION

[0002] Roadway markers are used on pavements along centerlines, edgelines, lane dividers, near fire hydrants or guardrail. Other roadwaymarkers are used as temporary lane dividers during construction phases.The most commonly used retro-reflective roadway markers using a housingfilled with structural polymeric material are based on Heenan U.S. Pat.No. 3,332,327, Balint U.S. Pat. No. 3,409,344, or Hedgewick U.S. Pat.No. 5,002,424.

[0003] Typically, this type of markers are produced in a processconsisting of three to four steps:

[0004] Firstly, injection molding of a thermoplastic housing (shell),integrally molded with one or two reflective faces.

[0005] Each inclined reflective face, integrally having multiple of cubecorner reflective elements within the inside surfaces of the opticallytransparent housing (shell).

[0006] Secondly, either the reflective faces within a shell or theentire inside surface of the shell coated with a reflective metallicsealer by a process known as vacuum metalizing. This metallic sealerneeded to seal the cube corner reflective elements so they retain partof their retro-reflectivity prior to the next step of filling the shellwith a thermosetting resinous material, such as epoxy or polyurethane toform a rigid structural body.

[0007] This resinous filler material encapsulates the metalized cubecorner reflective elements and agglutinate to interior surfaces of saidhousing, thereby provide the marker the impact resistance structuralbody.

[0008] Finally, a layer of relatively course sand or glass beadsdispersed over the outer surface of the filler material prior tosolidification of the filler material. Part of the sand particles willremain partially protruding above the planar surface of the marker base,thereby increase the adhesive welding parameter of the base surface.

[0009] This type of markers worked well for six or seven months,however, due to poor abrasion and incompatibility of the shell materialto the resinous filler material causes pealing of the reflective face orthe shell, thereby losing retro-reflectivity. Major disadvantage of thistype of structural body is that epoxy or urethane liquid fill systemsare expensive, inconsistence in quality and environmentally unfriendly.

[0010] Other major development in the pavement marker art has been made;this was achieved by eliminating the use of the metalized sealer for thecube corner reflective elements.

[0011] U.S. Pat. No. 4,726,706 to Attar, which is incorporated herein byreference in its entirety, divide the inside surfaces of the reflectivefaces into reflective cells, each cell will have multiple cube cornerreflective elements, the cells isolated from each other by partition andload carrying walls. However, instead of metelizing the inside surfaces,the entire inside surfaces of the reflective faces has to be sealed by athin sheet prior to filling the shell with resinous structural polymers.

[0012] Likewise PCT/US2001/0048847 A1 to Khieu discloses a shell housingeither integrally made having multiple cube corner reflective elementswithin two inclined faces or a sheet of reflective elements adhered tosaid inclined faces. The entire inside surface with the cube cornerreflective elements must be sealed with a thin sheet prior to fillingthe housing with resinous material.

[0013] U.S. Pat. No. 6,126,360 to May discloses pavement marker havingunfilled shell (housing) and lower base plate with load carrying walls.

[0014] The housing (shell) is made of a composite material having twoinclined faces. Each inclined face is integrally formed with recessedarea (12 b) and (12 c). Each recessed area having multiple load-carryingwall (22) defining hollow cavity recesses (24).

[0015] A lens member (50) is welded to the load carrying walls (22)within the recessed areas (12 b) and (12 c) of the marker housing priorto welding the base plate (314).

[0016] The goal of this invention is to have a durable roadway markerwith high reflectance, low cost and utilizing the presently used shelllike housing that are monolithically formed including at least oneinclined reflective face with multiple cube corner reflective elementsand without the need to weld a lens sheeting to a sealed, recessedportion of a housing, or without the need to seal the reflectiveelements with a thin sheet prior to filling the housing. This inventionalso eliminates the need to fill the housing with resinous fillermaterial.

SUMMARY OF THE INVENTION

[0017] This invention provide a novel process of forming one piece,hollowed structural body that can replace the potting process for atypical epoxy filled reflective Pavement markers having one piece upperhousing (shell). The present invention also eliminates the process ofsealing the lens surfaces either within a secondary sealed, recessedregions of a housing or sealed with a thin sheet of plastic. This methodprovide a monolithically injection molded, one-piece, hollowedstructural body with a sealed and textured base area that provide largewelding parameter, thereby provide better adhesion to the pavement andhigher resistance to flexural stresses. The one-piece hollowedstructural body provides integrally formed load carrying walls that canbe welded directly to portion of the apexes of the cube cornerreflective elements, while retaining the apexes of the remaining cubecorner elements freely within air gaps inside the hollow cavitiesdefined by said load carrying walls.

[0018] Alternatively, if a housing (shell) such as Attar's 706 is used,the inside raised partition walls defining the reflective cells withineach reflective face can be used for agglutination onto said one-piecestructural body fabricated to match Attar's 706 housing interior.

[0019] The primary objective of this invention is to provide a processof manufacturing one-piece structural body, thereby replacing theprocess of potting the housing with a resinous filler material andpre-sealing the lens surfaces.

[0020] Another objective of this invention is to provide a raisedroadway marker made of high impact resistant material without the needto use composite material.

[0021] The surface of this reflective pavement marker can be abrasionresistant with high reflective index. The present invention furtherprovides a method of making two-piece raised roadway marker of anydesirable shape and configuration, such as, a marker with truncatedbody.

[0022] In accordance with still further aspect of this invention, themarker can be made for one or two way traffic usage. Having anintegrally built-in cube corner reflective elements provides durabilityand cost effectiveness.

DESCRIPTION OF THE DRAWINGS

[0023]FIG. 1 is an isometric view showing a typical reflective pavementmarker housing and the preferred one-piece hollowed structural body.

[0024]FIG. 2 is a plan view of one of the preferred one-piece hollowedstructural body.

[0025]FIG. 3 is a cross section through line 3-3 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0026] Greatly enhanced hollowed structural body replacement can befabricated in one piece for pavement markers of the type that requirepotting or filling an integrally formed housing (shell) 10 with resinouspolymeric filling material. This method will also eliminate previousarts needs to seal the protruding apexes of cube corner reflectiveelements in air pockets defined by energy directors within a recessedportion of the reflective faces of a housing. This invention alsoeliminate applying thin sheeting to seal such exposed apexes of the cubecorner reflective elements prior to filling the housing 10 with aresinous polymeric filling body or metelizing the reflective elementsprior to such structural potting of said housing 10.

[0027] This invention's one-piece hollowed structural body 20, shown inFIG. 1, is monolithically made comprising of two regions, a sealedplanar base region 28 with textured and slightly grooved surface formaximizing the marker's adhesion to the roadway surface and an upperportion comprising of a top 21, two sides 22 and two inclined faces 23with hollowed cavities 24 defined by partition & load carrying walls 26.

[0028] The upper-hollowed surfaces of structural body 20 are formed toexactly conform to the interior of any specific shell like housing 10surface configuration. Typically, a roadway marker of this type hasfront and back planar-inclined surfaces for retro-reflection, twoinclined or arcuate sides and a top surface. Various sizes of this typeof reflective markers are used. Generally the exterior have either 2 by4, 2.5 by 4, 3 by 4 or 4 by 4-inch base dimensions.

[0029] This invention monolithically formed hollowed structural body 20is directly agglutinated to portion of the interior apexes of thebuilt-in cube corner elements of housing (shell). thereby leaving 80% ofthe protruding apexes of cube corner reflective elements freely openwithin correspondently formed hollow cavities at the upper region of thestructural body 20.

[0030] Presently, there are several manufacturing groups that utilizeprocesses based on Heenan's U.S. Pat. No. 3,332,327, Balent U.S. Pat.No. 3,409,344, Hedgewick U.S. Pat. No. 5,002,424 or Attar's U.S. Pat.No. 4,726,706. All such processes can easily eliminate at least twomajor steps that are presently used for assembling a reflective pavementmarker. This can be achieved by simply replacing the liquefied polymericfilling process with this invention one-piece hollowed structural bodythat can be formed to fit exactly within the interior of any existinghousing (shell) 10. By agglutinating or sonic welding an existinghousing (shell) 10 to a preformed one-piece hollowed structural body 20,the sealing or metal coating of the cube corner elements is thereforeeliminated.

[0031] The present method is not only environmentally friendly, providemaximum base adhesion surface to the roadway, but it is also costeffective due to the hollowed body design.

[0032] By eliminating the liquefied filling or potting process, therewould be no need fore the additional process of sealing the protrudingcube corner reflective elements with a thin sheet.

[0033] Referring to the illustrated drawings of this invention, FIG. 1shows a typical housing (shell) 10 with a top planar surface 18, twoinclined sides 16 and a reflective face 12 with an integrally formedinterior surface having multiple cube corner reflective elements 14.

[0034] A separate, monolithically formed, hollowed structural body 20can be fabricated by injection molding process to correspond exactly tothe interior surfaces of said housing (shell) 10. Structural body 20typically can be formed having an upper surface with multiple hollowcavities 24, partition and load carrying walls 26 with wedged shaped topsurfaces and a sealed, textured planar base surface 28.

[0035] Each load-carrying wall 26 is having a top surface 26 b thatwould be slightly textured and contoured to correspond exactly to theinterior surface of the housing 10 to which it will be agglutinated. Theload-carrying walls 26 that are directly beneath the apexes of saidmultiple cube corner reflective elements 14, within each interior of areflective face 12, would have slightly wedged top surfaces 26 b. Thesetapered top surfaces 26 b of load carrying walls 26 would minimize theagglutinating surfaces to the protruding apexes of cube cornerreflective elements 14, whereby allowing maximum portions of such cubecorner elements 14 to function freely within the hollowed cavity regions24.

[0036] Various agglutination processes can be used to weld themonolithically formed structural body 20 to a housing 10. Preferablysonic welding method can be used. Alternatively, a compatible,transparent adhesive such as an epoxy or polyester can be applied.

[0037] Using shell 10 as a typical example resembling the shell used forAttar's U.S. Pat. No. 4,726,706. The interior surface of the reflectiveface 12 can be used with or without any partition walls definingmultiple reflective cells.

[0038] The housing shown in FIG. 1 having the interior surface ofreflective face 12 without partition walls; instead it has the entireinterior surface integrally formed with either the micro size or thestandard, commonly used cube corner reflective elements 14. The novelaspect of this application is that these multiple cube corner reflectiveelements 14 would not be sealed in a separate area or be coated withmetallic film as a sealer and it would not need a preformed recessedarea within the housing 10. The outer shell (housing 10) will bedirectly agglutinated to the load carrying walls of this monolithicallyformed structural body 20, thereby sealing and protecting nearly 80% ofthe cube corner reflective elements within the hollowed cavities of thestructural body 20.

[0039] Polymers such as acrylic or polycarbonate can have both, thedesired optical transparency for the reflective faces 12 as well as thestructural and tear resistance strength. Alternatively, somemanufacturer sonically agglutinate the optical faces made of acrylic orpolycarbonate to an ABS housing (shell) 10, thereby allowing the use ofopaque pigmentation for the housing surface.

[0040] The commonly used cube corner reflective elements 14 for thistype of housings (shells) 10 are the standard types; as per theoriginally recommended prisms of Heenan U.S. Pat. No. 3,332,327 and alsoused for Attar U.S. Pat. No. 4,726,706.

[0041] However, it is recommended that finer or small micro cube cornerprism be used to optimize both the retro-reflectivity as well aslimiting the welding parameter beneath the protruding apexes of cubecorner reflective elements.

[0042] The preferred polymeric material to make such hollowed structuralbody 20 is ABS thermoplastic. However, even a recycled ABS, acrylic,polycarbonate, reinforce or non-reinforced engineered plastic can beused, provided it would be compatible for agglutination to thecorresponding housing 10 material to which it will be welded.

[0043] Typically, the tooling needed for fabrication of this type ofhollowed structural body 20 is a simple injection-molding mold. Noadditional slides or other moving parts are necessary.

[0044] The method of agglutinating the one-piece hollowed body 20 to thehousing 10 can be achieved either by applying a thin thermosettingadhesive material to the upper surfaces of the hollowed structural body20, then firmly inserting the housing (shell) onto the adhesivesurfaces. Alternatively, agglutination of the one-piece hollowedstructural body 20 to the interior of housing 10 can be achieved bysonically welding the two parts.

[0045] Other advantages of this direct agglutination of the cube cornerreflective elements 14 to the top surfaces 26 b of load carrying walls26 is that even the cube corner elements that would be agglutinated tosaid surfaces would retain air gaps entrapped behind the remaining threesurfaces of each cube corner element, thereby partial retro-reflectivitycan be attained from these agglutinated cube corner elements.

[0046] It is understood that various changes or modification can be madewithin the scope of the appended claims. All such modifications fallwithin the true scope and spirit of this invention.

What is claimed:
 1. A reflective pavement marker comprises of an uppershell like housing and a monolithically formed one-piece hollowedstructural body agglutinated to said upper housing; said shell likehousing having a top surface, two inclined side walls and two planarinclined reflective faces, at least one of said planar reflective faceshaving an interior surface with plurality of cube corner reflectiveelements, said shell like housing can be made from a polymeric,thermoplastic selected from a group of polycarbonate or acrylic; saidmonolithically formed one-piece hollowed structural body having anintegrally sealed, planar base surface with textured surface foragglutination to a substrate such as roadway surface, and an upperhollowed region that is divided into a top, two sides and two inclinedfront and back faces corresponding to the interior contours of saidshell like housing, said planar sealed base region can be divided intoshallow recesses, said upper hollowed cavities are having sealed endsslightly above the sealed planar base region, said upper hollowedcavities are defined by partition and load carrying walls, said loadcarrying walls having tapered sides and a textured or wedged shaped topsurfaces that correspond to the interior contours of said shell likehousing, said monolithically formed one-piece hollowed structural bodycan be made of a compatible polymeric material, said polymeric materialcan be recycled or virgin material selected from either ABS,polycarbonate, acrylic with or without additive filler materials forstrength or pigmentation, said shell like housing can be welded to saidmonolithically formed structural body utilizing sonic welding process ordirect agglutination methods.
 2. The reflective pavement marker of claim1, wherein said monolithically formed one-piece hollowed structural bodybeing agglutinated or sonic welded onto the interior surfaces of saidshell like housing and wherein said interior surfaces of reflectivefaces providing portions of the protruding apexes of said cube cornerreflective elements for agglutination to a correspondently tapered topportions of load carrying walls within said one-piece hollowedstructural body, whereby retaining the remaining cube corner reflectiveelements protruding freely within hollow cavities of said monolithicallyformed one-piece hollowed structural body.
 3. The reflective pavementmarker of claim 1, wherein said shell like housing can have theinteriors of said two reflective faces divided into reflective cells,said reflective cells each having plurality of cube corner reflectiveelements, said reflective cells are separated from each others bypartition walls, said partition walls are spaced to correspond to thesize and shapes of partition and load carrying walls within saidone-piece hollowed structural body to which it will be agglutinated orsonically welded.
 4. A method of fabricating the reflective markercomprising the steps: Injections molding the shell like housing usingeither one step molding process where one type of transparent polymericthermoplastic is utilized, or using a two step molding, where a preformed transparent lens plates are pre inserted in the mold and theremaining surfaces of a shell like housing is formed in a the shape of adesired reflective pavement marker.
 5. The method of claim 4, whereinthe entire one-piece hollowed structural body is monolithicallyinjection molded in one step cycle, said monolithically formed one-piecehollowed structural body having the entire upper surface defined withhollowed cavities.
 6. The method of claim 4, wherein a thermosettingadhesive is applied onto the entire upper surfaces of said one-piecehollowed structural body prior to insertion firmly into the shell likehousing to form the desired reflective pavement marker.
 7. The method ofclaim 4, wherein the monolithically formed one-piece hollowed structuralbody can be sonically welded into the interior of the shell likehousing, thereby forming the desired reflective pavement marker, saidtop surfaces of the partition and load carrying walls to be partiallyfused to portion of the correspondingly formed interior surfaces of saidshell like housing and to portion of the protruding apexes of the cubecorner reflective elements within the interior of the two reflectivefaces of said shell like housing.
 8. The method of claim 4, whereineither the entire outside surface of the shell like housing or thereflective faces can be coated with abrasion resistance hard carbon oraluminum oxide film, utilizing chemical vapor deposition methods.